Cylinder head attachment



Aug. 16, 1938. R. CHILTON ET Aa.

l CYLINDER HEADATTACHMENT FiledA March 11*?, 193s INVENTOR. ROLANDc/fJLro/v PUDO H f. GAGG.

. 1Q l f l AORNEY.

Patented Aug. 16, 1938 UNITED STATES PATENT OFFICE CYLINDER HmmATTACHMENT Application March `17,

4 Claims.

This invention relates to the attachment of cylinder heads to cylinderbarrels, and particularly comprises improvements in the screw threadtype of joint now in use in air-cooled aircraft 5 engines.

'The conventional construction comprises an .aluminum head screwed ontoa steel barrel and many failures in the aluminum are caused by fatiguecracks engendered by the stress concentration which occurs at the sharpcorners of the threads.

To overcome this difficulty it has been sought to use forged rather thancast aluminum alloys for the heads, but this involves a great increasein fabrication cost, in view of the excessive amount of machiningrequired in producing the required linning from solid forgings.-

The prime object of the present invention is to eliminate from thestressed portion of the head material the stress concentrations due tothe threads, and thus to increase the strength and fatigue resistance ofthe structure.

The drawing is a fragmentary axial section through a cylinder headembodying the invention. In this drawing the head comprises the lowerportion Il] equipped with the valve seats I2 and fins, shown as to theirboundaries only, by the dotted lines I4. A conventional cylinder barrelI6 has screw threads I8 and i'lns 20 there- 30 on. According to theprovisions of this invention, instead of forming the companion threadsin the material of the head I0, an annular recess having a very largeradius or fillet 22 is provided and into this recess there is expanded,as by roll- 35 ing, a ring 24 preferably of forged aluminum material.After the ring 24 is expanded into the head l Il, the bore of the ringis threaded. Thereupon, the cylinder head, with the ring 24, is broughtto an elevated temperature and is assembled to the steel barrel IE, thethreads of the ring 24 engaging the threads I8 of the barrel I6, and thesmooth bore of the head itself engaging the smooth surface of thecylinder below the threads.

It will now be seen that all sharp corners have 45 been removed from thematerial of the head III and the large radius 22 substituted; thiscompris- 1936, Serial No. 69,290

, While we have described our invention in detail in its presentpreferred embodiment, it will be obvious to those skilled in the art,after understanding our invention, that various changes andmodifications` may be made therein without de- 5 parting from the spiritor scope thereof. We aim in the appended claims to cover all suchmodications and changes.

What is claimed is: I

1. In a joint, an integral outer head member of material of low strength`and fatigue resistance, said member having a cylindrical recess, aninner cylinder member engaging within said recess and extendingtherefrom, the recess having an annular groove, and a high strength andfatigue resistant ring in screw threaded engagement with saidcylindrical member and engaging within said groove, whereby tensilestress between respective members is carried through said ring.

2. In apparatus of the class described, an integral head member having acylindrical sided recess and an annular groove therein, said groovehaving an arcuate profile, a ring of material stronger than the memberfilling said groove and having threads formed in its recess, and acylinder smoothly engaging within said recess having threads engagingthe threads of said ring.

3. In a joint, a light alloy integral head member having a recess and anannular groove within the recess, a ring of material stronger than themember within said groove and in contact with the groove surface, saidring having screw threads formed on the bore thereof, and an externallythreaded member screwed into said ring and smoothly engaging the surfaceof said recess. 35

4. In a. joint between an annular integral head member and a tubemember, the head member being of relatively weak material of such acharacter .as not to have adequate strength for screw threadedengagement with the tube member, 40 said head member having a smoothcylindrical recess and an annular groove of arcuate prole in thecylindrical part of the recess, a strong ring capable of supportingscrew threads, and having same in its bore, disposed within said grooveand in bearing engagement with the surface thereof, said tube membersmoothly engaging said bore and having external threads in screwengagement with threads of said ring, whereby relative tensile stressbetween said head and tube members is resisted by the strong ringcompressively bearing on the surface of the head member groove and bythe screw threaded connection between the tube and ring.

ROLAND CHILTON. 55 RUDOLPH F. GAGG.

